'ClsClassImpl' instances created by the platform contain synthetic
enum methods (added by 'ClassInnerStuffCache.calcMethods()'). Such
convention is common in IntelliJ (see KT-36095 and
'9a8b345adaded83fe13980a28db5d9f9acc7450d' in the IntelliJ repository).
This commit makes Kotlin's stub-based classes consistent with the
convention. Instead, a filter is added in place of 'ClsClassImpl' usage.
See also the following commits:
- 7c86911f44
- 43468c6d55
'KotlinClassInnerStuffCache' was copy-pasted from the platform's
'ClassInnerStuffCache' several years ago. After J2K and other changes,
it became quite dirty.
Besides cleaning things up, enum synthetic method handling have
significantly improved. Before, such methods were handled only in
'processDeclarationsInEnum', and 'getMethods()' didn't return them.
This led to inconsistent behavior and was reason for providing special
ad-hoc support in '1b6ded600518176b21cc308ed3e032ef8d04cc90'.